1)k^2+2kn+n^2 = (k+n)^2
2) n^2-8n+16 = (n-4)^2
3) 16k^2+40kn+25n^2 = (4k+5n)^2
4)k^2n^2-2kn+1 = (kn-1)^2
1)k^2+2kn+n^2 = (k+n)^2
2) n^2-8n+16 = (n-4)^2
3) 16k^2+40kn+25n^2 = (4k+5n)^2
4)k^2n^2-2kn+1 = (kn-1)^2